The major objective of the proposed research is to determine the advantages of binaural hearing among normal and hearing impaired individuals by exploring localization and directional hearing abilities during conditions in which the head is immobilized as contrasted to conditions in which head movement is encouraged and measured. Further investigations will determine the relationships between localization ability and speech reception when stimuli are presented in backgrounds of competition. An optical device for measuring head movement has been developed and experiments on localization ability for binaural and monaural listeners is in progress. BIBLIOGRAPHIC REFERENCES: Dirks, D. and Kamm, C. Psychometric Functions for Loudness Discomfort and Most Comfortable Loudness Levels. J. Speech Hear. Res. 19, 613-726, 1976. Kaplan, H., Gilman, S. and Dirks, D. Properties of Acoustic Reflex. Accepted for publication, February 1977. Ann. Otol. Rhinol. Laryngol.